Device for maintaining a working fluid under a predetermined pressure

ABSTRACT

A device for maintaining in a delivery pipe a working fluid under a determined pressure, using a source of pressurized auxiliary fluid communicating with a chamber of variable volume, in which the pressure of the auxiliary fluid varies in an inverse proportion with respect to the volume of the chamber. This device comprises an assembly of at least two jacks and at least one connecting rod articulated separately on first constituting elements of a first and a second jack of the assembly. The cylinder of the first jack is connected to the source of pressurized fluid and forms the chamber of variable volume and the cylinder of the second jack supplies the working fluid to the delivery pipe.

Castela et al.

DEVICE FOR MAINTAINING A WORKING FLUID UNDER A PREDETERMINED PRESSURE Inventors: Andre Castela, Le Mesnil Le Roi;

Philippe Joubert, Meudon La Foret, both of France Assignee: Institut Francais du Petrole, des

Carburants et Lubrifiants, France Filed: May 2, 1973 Appl. No.: 356,435

Foreign Application Priority Data May 2, 1972 France 72.16071 June 23, 1972 France 72.22953 June 23, 1972 France 72.22954 U.S. Cl. 60/533; 92/118; 92/140 Int. Cl. F15b 7/00 Field of Search 60/5 33, 579, 580; 92/117, 92/118, 140

References Cited UNITED STATES PATENTS 12/1932 McLeod 92/118 June 17, 1975 2,668,450 2/1954 Crookston et al. 92/1 18 2,922,399 1/1960 Panissidi et al. 92/! 17 3.550.376 12/1970 Esteve 60/580 Primary Examiner-Martin P. Schwadron Assistant Examinerl-l. Burks, Sr. Attorney, Agent, or FirmCraig & Antonelli (57] ABSTRACT A device for maintaining in a delivery pipe a working fluid under a determined pressure, using a source of pressurized auxiliary fluid communicating with a chamber of variable volume, in which the pressure of the auxiliary fluid varies in an inverse proportion with respect to the volume of the chamber. This device comprises an assembly of at least two jacks and at least one connecting rod articulated separately on first constituting elements of a first and a second jack of the assembly. The cylinder of the first jack is connected to the source of pressurized fluid and forms the chamber of variable volume and the cylinder of the second jack supplies the working fluid to the delivery pipe.

18 Claims, 5 Drawing Figures PATENTEDJUN 17 I975 SHEET PATENTEDJUN 17 ms 3,889 166 saw 3 (g/cm, H65

sum

1 DEVICE FOR MAINTAINING A WORKING FLUID UNDER A PREDETERMINED PRESSURE The invention relates to a device for maintaining a working fluid under a predetermined pressure. This device is used in combination with a source of pressurized fluid and includes a chamber of variable volume, such as the cylinder of a jack in which the fluid pressure varies in inverse proportion with respect to the volume of the chamber. By using this device it becomes possible to adjust the pressure of the working fluid to a value which may be very close to a pressure preselected for each value of the chamber volume.

Pressure regulating devices have already been proposed which comprise at least one jack pivotally mounted about one stationary point of its constituting elements (i.e., the cylinder and the piston with its rod), one point of the other constituting element of the jack being moveable along a determined path, with respect to which the jack remains inclined when pivoting about said stationary point.

The piston of this jack is subjected to the pressure of a fluid supplied from a source of pressurized fluid and the jack exerts in turn a pressure on a working fluid whose actual pressure is thus a function both of the pressure of the fluid in said source and of the cosine of the inclination angle of the axis of the pivoting jack with respect to said determined path.

Thus, by adjusting the different constructional parameters of the device, it becomes possible to obtain, in response to a given law of variation of the fluid pressure in the source of pressurized fluid, a determined law of variation of the working fluid pressure as a function of the variations in volume of the chamber and the resulting law of variation may be close to an ideal desired law of variation.

The present invention provides a new device for maintaining a working fluid under a substantially determined pressure by applying to the pressure variations of a fluid supplied by a source of pressurized fluid of the above-considered type, a corrective factor which is no longer a function of the cosine of a variable angle, but depends on the ratio of trigonometric functions of variable angles, which ratio varies in a broader interval.

The device according to the invention maintains in a pipe a working fluid at a determined pressure, by using a source of pressurized auxiliary fluid in communica tion with a chamber of variable volume, the pressure of the auxiliary fluid varying in inverse proportion with respect to the volume of the chamber. This device cornprises an assembly of at least two jacks and at least one connecting rod articulated separately with a first constituting element of each of a first and a second jacks of said assembly, the cylinder of a flrst jack of said assembly forming said chamber of variable volume and the cylinder of a second jack of said assembly supplying said pipe with working fluid.

The invention will be better understood from the following description of non-limitative embodiments thereof, illustrated by the accompanying drawings wherein:

FIG. 1 illustrates a first embodiment of the invention comprising two jacks and a connecting rod forming a triangular system,

FIG. 2 illustrates a second embodiment of the invention. comprising two jacks and an assembly of connecting rods forming a quadrilateral system;

FIG. 3 shows a specific embodiment of the device illustrated by FIG. 2;

FIG. 4 shows an alternative embodiment of the device illustrated by FIG. 3;

FIG. 5 is a graph indicating, for different positions of the device according to FIG. 4, the pressure exerted by the accumulator and the pressure applied to the working fluid plotted versus the stroke of the jack.

In FIG. 1, the source I of fluid under pressure, consists of an air-oil accumulator housing a bag 2 of pressurized gas.

The device according to the invention comprises two regulating jacks 3 and 4 whose axes form an angle therebetween. The cylinders of the jacks are, for instance, stationary and a rigid connecting rod 5, of a determined length, connects to each other the piston rods of the jacks, said connecting rod 5 being articulated with these piston rods. The jacks 3 and 4 and the connecting rod 5 form a deformable triangular system in which the connecting rod 5 is inclined on the jack 3 by a variable angle 7 and on the jack 4 by a variable angle B, the third angle of the triangle, opposite the connecting rod 5, being a.

The cylinder of the jack 3 is connected to the accumulator 1 through pipe 16 and the cylinder of the jack 4 contains a hydraulic working fluid which is delivered to pipe 17 under a pressure:

S being the area of the piston ofjack 3, s the area of the piston of jack 4, 7,6 and or having the above-indicated meanings and P being the pressure prevailing in the accumulator l for the considered values of the angles 7 and B.

In the particular case where the jacks 3 and 4 are at right angles, cos B sin y and the pressure P, is:

P P S/s sin'y/cos'y P 5/5 tan y According to an alternative embodiment, the connecting rod 5 may be stationary and the cylinders of jacks 3 and 4 articulated about one and the same moveable articulation point.

The device illustrated by FIG. 2, comprises two regulation jacks 3 and 4, whose axes extend along the diagonals of a deformable quadrilateral formed by four connecting rods 10, ll, 12 and 13 of determined lengths, articulated to each other at points 6, 7, 8 and 9. One element (for example the cylinder) of the jack 3 is articulated at 8 and the other element (the piston rod) at 6. One element (for example the cylinder) of the jack 4 is articulated at 9 and the other element (i.e., the piston rod) at 7.

In the embodiment illustrated by FIG. 2, the axis of jack 3 and its articulation point are stationary, the articulation point 6 being moveable along the diagonal 6-8 of the quadrilateral.

The jack 3 is connected to the air-oil accumulator I through a pipe 16 and the jack 4 supplies pipe 17 with hydraulic working fluid.

In the embodiment illustrated by the drawing, the connecting rods form a parallelogram and the pressure P of the hydraulic fluid supplied by the jack 4 is:

P, P S/s sin y'lsin B'= P S/s sin ylsin B y and 7 being the angles formed respectively between the jack connected to the accumulator and the adjacent connecting rods of the parallelogram, ,B and B being respectively the angles between the jack supplying the working fluid at pressure P, and the adjacent connecting rods, S being the area of the piston of jack 3, s the area of the piston of jack 4 and P the pressure in the accumulator for the considered values of the angles y and B or 'y' and B.

For any quadrilateral, the pressure P is given by the formula:

P P S/: sin 'y'lsin B sin B'lsin 6 wherein 'y' is the angle between the jack 3 connected to the accumulator and a first connecting rod, the angle of the quadrilateral at the articulation 6 of the jack 3 with the first connecting rod, B the angle between the jack 4 supplying the working fluid at pressure P, and a second connecting rod, opposite to the first one in the quadrilateral and 9' is the angle of the quadrilateral at the apex of which the jack articulated with the second connecting rod.

In the construction of the device according to the invention. those skilled in the art will be able to select the values of such parameters as the lengths of the connecting rods, the angles 7, B, -y' and B and the ratio of the cross sectional areas S/s of the pistons of the jack in accordance with the particular conditions of use.

Modifications may be brought without departing from the scope of the invention, in particular the connecting rods may form a deformable quadrilateral of the concave or convex type or with intercrossing sides. One of the jacks, for example jack 3, may have one stationary articulation (articulation 8), while the other articulation is displaceable along a determined path, which is different from the direction defined by a diagonal of the quadrilateral.

The particular embodiments of the device according to the invention, as illustrated by FIGS. 3 and 4, comprise two regulation jacks 3 and 4 whose elements (pis ton rods and cylinders) are coupled through connecting rods l0, l1, l2 and 13, articulated at 6, 7, 8 and 9 at the apices of a quadrilateral having perpendicular diagonals, this quadrilateral being a rhomb in the two illustrated embodiments.

One articulation point of one jack, for example point 8 of jack 3 is stationary while the other articulation point is displaceable along a diagonal of the quadrilateral (following the arrows).

One cylinder of a jack, for example jack 3, is connected to the accumulator through pipe 16 while the other supplies pipe 17 with hydraulic working fluid whose pressure is substantially:

P P S/s tan 6/2, 0/2 being the corresponding value of the half-angle of the quadrilateral at apex 8, S the area of the piston of jack 3 and s the area of the piston ofjack 4, P being the pressure in the accumulator l, for the considered value of the angle 6/2.

In the case where the quadrilateral with perpendicular diagonals, formed by the connecting rods 10, ll, 12 and 13, is not a rhomb, the half-angle 6/2 of this quadrilateral at its apex 6 is different from the angle 6/2 at apex 8 opposite to apex 6 and P,,= 1/2 P /5 (tan 6/2 tan 8/2) In FlG. 5, by way of example, there are plotted against the stroke C ofjack 3, expressed in meters, the variations of the pressure P within an air-oil accumula tor operating within the pressure range of from 100 to 300 bars, the corresponding variation of the volume of the gas in the accumulator being liters.

The regulating device has, in this particular embodiment. the shape of a rhomb and S/s l (i.e., the cross sectional area of jacks 3 and 4 have been chosen equal).

FIG. 5 also shows the curve of variation of the pressure P, of the working fluid in response to the stroke C of jack 3, this curve being very different from the curve representing the variation of P.

In the considered example, the angle 6/2 varies from 386/l0 to 674/10, in order to obtain two equal values of the pressure P, for the limit positions of the jacks.

By adjusting the parameters consisting of the ratio 5/5 and the variation range of the angles 6/2 and 8/2, anyone skilled in the art can adapt the curve of variation of the pressure P, to particular conditions of use.

What we claim is:

l. A device for maintaining a working fluid in a pipe under a determined pressure, making use of a source of pressurized auxiliary fluid in communication with a chamber of variable volume, in which the pressure of the auxiliary fluid varies in inverse proportion with respect to the volume of the chamber, said said comprising an assembly of at least two jacks, each of said two jacks being disposed at an angle with respect to one another, and each of said two jacks comprising two elements, said two elements including a cylinder and a piston rod; and at least one rigid connecting rod joining at least respective first elements of said two elements of each of fsaid two jacks of said assembly, the cylinder of a first jack of said two jacks of said assembly being connected to the source of pressurized auxiliary fluid and forming the chamber of variable volume, and the cylinder of a second jack of said two jacks of said assembly supplying a pipe with working fluid.

2. A device according to claim 1, wherein the second element of said two elements of said two jacks is stationary.

3. A device according to claim 2, comprising two jacks, wherein said angle constitutes a triangular system with said connecting rod, said triangular system being deformable by displacement of said first elements of said two jacks with respect to said second elements thereof.

4. A device according to claim 1, comprising two jacks and four connecting rods joined two by two, said connecting rods forming a quadrilateral, said first and second elements of said two jacks being respectively joined at the apices of this quadrilateral, and said two jacks having axes extending along the diagonals of said quadrilateral.

5. A device according to claim 4, in which one of said two jacks has a stationary joint, and a second joint displaceable along a predetermined path.

6. A device according to claim 4, in which one of said first and second elements of one jack of said two jacks is kept stationary.

7. A device according to claim 6, in which the quadrilateral is a parallelogram.

8. A device according to claim 6, in which said quadrilateral is a rhomb.

9. A device according to claim 4, in which said connecting rods form a convex quadrilateral.

10. A device according to claim 4, wherein said connecting rods constitute a quadrilateral having intercrossing sides.

11. A device according to any of claims 6, in which the jacks of said assembly are perpendicular to each other.

12. A device according to claim 10, in which the jacks of said assembly are perpendicular to each other.

13. A device according to claim 11, in which the jacks of said assembly are perpendicular to each other.

14. A device according to claim 1, wherein said at least one connecting rod is pivotally joined to said first elements of each of said two jacks.

15. A device according to claim 4, in which said connecting rods form a concaved quadrilateral.

16. A device according to claim 1, wherein each of said first elements of said two jacks forms a respective variable angle with said at least one rigid connecting rod, and said working fluid is maintained at the determined pressure which is a function of both the pressure of said pressurized auxiliary fluid and a ratio of trigonometric functions of at least one of said respective variable angles.

17. A device according to claim 16, wherein said determined pressure of said working fluid is a function of a ratio of trigonometric functions of each of said respective variable angles.

18. A device according to claim I, wherein said source of pressurized auxiliary fluid includes a gas-fluid accumulator containing a source of pressurized gas having a variable volume. 

1. A device for maintaining a working fluid in a pipe under a determined pressure, making use of a source of pressurized auxiliary fluid in communication with a chamber of variable volume, in which the pressure of the auxiliary fluid varies in inverse proportion with respect to the volume of the chamber, said said comprising an assembly of at least two jacks, each of said two jacks being disposed at an angle with respect to one another, and each of said two jacks comprising two elements, said two elements including a cylinder and a piston rod; and at least one rigid connecting rod joining at least respective first elements of said two elements of each of fsaid two jacks of said assembly, the cylinder of a first jack of said two jacks of said assembly being connected to the source of pressurized auxiliary fluid and forming the chamber of variable volume, and the cylinder of a second jack of said two jacks of said assembly supplying a pipe with working fluid.
 2. A device according to claim 1, wherein the second element of said two elements of said two jacks is stationary.
 3. A device according to claim 2, comprising two jacks, wherein said angle constitutes a triangular system with said connecting rod, said triangular system being deformable by displacement of said first elements of said two jacks with respect to said second elements thereof.
 4. A device according to claim 1, comprising two jacks and four connecting rods joined two by two, said connecting rods forming a quadrilateral, said first and second elements of said two jacks being respectively joined at the apices of this quadrilateral, and said two jacks having axes extending along the diagonals of said quadrilateral.
 5. A device according to claim 4, in which one of said two jacks has a stationary joint, and a second joint displaceable along a predetermined path.
 6. A device according to claim 4, in which one of said first and second elements of one jack of said two jacks is kept stationary.
 7. A device according to claim 6, in which the quadrilateral is a parallelogram.
 8. A device according to claim 6, in which said quadrilateral is a rhomb.
 9. A device according to claim 4, in which said connecting rods form a convex quadrilateral.
 10. A device according to claim 4, wherein said connecting rods constitute a quadrilateral having intercrossing sides.
 11. A device according to any of claims 6, in which the jacks of said assembly are perpendicular to each other.
 12. A device according to claim 10, in which the jacks of said assembly are perpendicular to each other.
 13. A device according to claim 11, in which the jacks of said assembly are perpendicular to each other.
 14. A device according to claim 1, wherein said at least one connecting rod is pivotally joined to said first elements of each of said two jacks.
 15. A device according to claim 4, in which said connecting rods form a concaved quadrilateral.
 16. A device according to claim 1, wherein each of said first elements of said two jacks forms a respective variable angle with said at least one rigid connecting rod, and said working fluid is maintained at the determined pressure which is a function of both the pressure of said pressurized auxiliary fluid and a ratio of trigonometric functions of at least one of said respective variable angles.
 17. A device according to claim 16, whErein said determined pressure of said working fluid is a function of a ratio of trigonometric functions of each of said respective variable angles.
 18. A device according to claim 1, wherein said source of pressurized auxiliary fluid includes a gas-fluid accumulator containing a source of pressurized gas having a variable volume. 